Patrol ships are necessary to protect coastlines and fleets, but they're far from ideal right now. You need big, bulky vessels, and the human crews are either faced with the tedium of an uneventful trip (if they're lucky) or threats that a lone ship is ill-equipped to face. Rolls-Royce might have a better way: it just unveiled plans for an autonomous patrol ship that would eliminate many of these headaches, and would even be relatively eco-friendly. The ship will use a combination of artificial intelligence and sensors to get around instead of a crew, with modular systems letting it change roles between missions (for example, a drone launching pad). This should not only let it operate for long stretches (up to 100 days) without subjecting humans to risk or sheer boredom, but allows for a smaller design that's cheaper to run.